Drill



June 11, 1940. v T. H. STANCLIFF DRILL Filed Dec. 13,- 1938 ZSheets-Sheet 1 Patented June .11 1940 v UNITED STATES PATENT OFFICE Thomas H. Sta'ncliil'. Houlton,.'1ex., assignor to Reed Boiler Bit Company, Houston, Tex, a

corporation of Texas Application December 13,1938. Serial so. 245,380 f I 2 Claims. (oi; 255-11) This invenuen relates to deep well drilling apparatus, and. specifically to bits.

Although not limited thereto itwm be found particularly useful in rock bits of the roller type. In bits of that-type the diameter of the hole is determined by the so-called side rollers which are customarily mounted to rotate about axes extending downwardly and inwardly toward the center of the bit. In the past these side roller cutters have been formed with cutting teeth which come to a sharp corner adjacent the outermost portion of the cutter which -is adapted to cut at the bottom of the hole'and determine the This is because as the cutter. rolls around the.

about a vertical axis about the inside or avertical cylindrical hole a true rolling action will take place but if the same cutter be rotated about a horizontal axis and'made to traverse the bottom of a hole its outer cuttlng't'eeth will constantly be di ging into the wall oi the hole. This digging in action becomesless and less as the cutter axis is tilted toward the vertical. but where it is tilted only part way as in the case of the usual side roller cutter, and the diameter of this cutter is kept large, as it preferably is for purposes of structural strength, et cetera, these teeth will still dig in to a more or less extent. This digging in action tends to quickly wear away the outer portions of these teeth and thus spoil that portion of the bit which determines the gauge of the bore hole being formed. This naturally necessitates frequent replacement of the'bits simply because of the action of the cutter in scraping the hole to a larger diameter than is desired in the finished hole.

It is, therefore, an object of thisinvention to provide a bit which will give longer wear than those heretofore used. It is a further object of this invention to provide a bit which will be capable of maintaining the gauge of a hole over a longerperiod of use 5 than bits heretofore employed.

Another object of this invention is to provides.

bit which will eliminate to a large extent the unnecessary scraping oi the sides of the hole during the operation of the bit. Other objects will hereinafter appear. Referring now to the drawings: Fig. 1 illustrates a bit constructed in accord- 3 ance with this invention, the same being shown partly in vertical cross section for the purpose of illustration.

Fig. 2 is a fragmentary side elevation of one of i the slide cutters forming part of the bit shown in Fig.

Fig. 3 is a diagrammatic illustration for the 2d purpose'of comparing the amount of side wall scraping done by. various types of side cutter teeth.

Fig. 4 is a diagrammatic illustration showing aplan view of the bottom of a hole and the. paths taken by cutter teeth of various shapes shown with reference to the side walls of the hole.

Fig. 5 is a diagrammatic vertical cross section of a portion of the bottom of a well being cut by a bit constructed in accordance with this invention and illustrating the scraping action of various portions of the teeth carried thereby.

Referring now more specifically to the drawings, the numeral l indicates the usual bit head having a threaded upperend 2 adapted to receive a drilicollar on the lower end-of a drill stem, and the numeral 3 indicates the usual cross roller cutter employed in this type of bit. "These cross roller cutters are rotatably mounted upon a shaft 4, the central portion ofzwhich is in part supported by means of a bridge 5. Thisbr-idge 5 has oppositelydisposed upwardly and outward ly inclined bearing portions 6 and 1 ad'aptedto rotatably mount the side roller cutters 8. Suit able balland roller bearings 9 and Ill, respectively, may be employed within these cutters. 0n the opposite ends of the bridge 5 there are provided upstanding lugs H and I2 which are welded or otherwise secured as at l3 and M to the body of the bit.

As is well known, the cross rollercutters dare adapted to cut the central portion of the bottom of the hole while the side roller cutters are adapted to cut the outer portion of the bottom of the hole and determine the gauge or diameter 55 of thehole. .Heretofore it has been customary for the teeth I! of these cutters to extend outwardly to a sharp corner, as shown in dotted lines at It in Fig. 5, and then upwardly along the outside of the cutter. In accordance with this invention, the teeth I! are terminated at a point Referring now to Figs. 3 and 4, there has been illustrated a comparison between the amount of scraping done by the two corner portions Ill and IQ of the cutter teeth provided by this invention and the amount of scraping which would be done by the old form of cutter extending to a single sharp comer It to determine the gauge size of the bit. In Fig. 4 the numeral 20 designates the outer wall of the hole which is to be formed while the numeral 2| designates the edge of the shoulder 22 which would be formed bythe cutting parts l1 and I9 around the bottom of the hole.

Now, if the cutter teeth beextended to a single sharp corner i6, Fig. 5, these corners will lie along the line 23 which takes the form of an ellipse when viewed from above as shown in Fig. 4. This ellipse would intersect the line 20 which indicates the outside wall of the hole beginning at the point 24 and extending to the point 25 where the cutter is iheohtact with the bottom of the hole. Referring to Fig. 5, it will be seen that the vertical distance between the point 24 and the bottom of'the holefor a given size of hole and cutter will be, for example, three quarters of an inch. Still referring to Fig. 5, the path which this point on the cutter would take in moving to the bottom of the hole and up again would be substantially along the dotted lines 26, and

' throughout this entire distance along the dotted line 26 the tooth corner It would be scraping into and digging intothe side wall of the hole,

ner of the cutter tooth.

Now, with a cutter formed according to this invention, the tooth corner I! would move downwardly along the line 2'l crossing .the line 2| whichindicates the size of the hole that this portion of the cutter will cut at the bottom at the point 28. The shoulder which is formed by this type of cutter, however, is for the size of the path and hole taken by way of example only one quarter of an inch, whereas the point 28, as shown in Fig. 5, is more than three quarters of an inch above the bottom of the hole. Therefore, the scraping of the tooth comer II will not begin until this tooth corner moves downwardly to the upper end of the shoulder at which time it will begin scraping and will scrape a distance however, that the overlapping between the point 32 and the point 25 is very slight so that these teeth although they will scrape from the point 82 to the point 26 will not in an appreciable amount and will not cause aniappreciable-en-M V largement of the hole. By the same token, they j will not be greatly worn by the scraping action.

Furthermore, referring to Fig. 5, a tooth at the point 32 will move downwardly along the dotted line 33 and back again and this line will represent the entire scraping action of the corner I! on one tooth. The vertical distance between the point 32 and the top of the shoulder where the line terminates is only-one eighth of an inch in the size of the bitTbeing used for an example.

Thus, by this inventionit will be seen that instead of having a scraping action for a vertical distance of three quarters of an inch for each tooth in a given size of bit (9"). which scraping action will all be done by the gauge maintaining portion of the cutters, a bit has been produced having two cutting parts, one of which will scrape only one quarter of an inch and the other,

which isthe gauge maintaining part, will scrape onLv one eighth of an inch. This makes a total in the total amount of the scraping action, it will be seen that almost all of this scraping action is taken by a part of the bit which does not serve to .maintain the gauge of the hole. The gauge maintaining part of the bit will for this reason wear much longer and the life of the bit as a whole will be accordingly increased. The wear of this 1 gauge maintaining part of the bit will be still further decreased by the fact that although this part scrapes for a vertical distance of one eighth of an inch, this scraping does not dig deeply into I the side wall of the hole butdigs only a relatively inconsequential amount.-

From the foregoing it will be seen that a means has been provided which will greatly reduce the wear taking place upon the cutting teeth of drilling bits of the type to which this invention relates, without in any way making it necessary to reduce the size or eii'ectiveness of the cutting parts or to alter the disposition of the cutters with respect to each other in any way which might reduce the efiiciency of the bit as a cutting or digging implement. Means has also been provided for carrying out all of the otherobjects and advantages sought by this invention.

Having described my invention, I claim:

1. A drill bit including a side rollercutter, said cutter having cutting portions thereon adapted to cut the outer annular portion of a hole being drilled of slightly less than the desired gauge, and other cutting portions on the same cutter outwardly of and stepped upwardly from said first cutting portions adapted to cut at a higher level than said first cutting portions to enlarge said smaller hole to the desired gauge.

2. A drill bit including a cutter thereon mounted for rotation about an axis at an angle with respect to the axis of the bit and to cut the bottom and side of the hole being drilled,-said cutter having a cutting 1:i art of greater radius adapted to cut a path at the bottom of the hole of less diameter than the diameter of the hole desired, and a second cutting part of less radius disposed outwardly of and non-continuous with said first cutting part adapted to enlarge said hole to the desired gauge. 

